This invention relates to systems for testing electronic circuits by applying and/or measuring electrical signals and, more particularly, to electronic circuit test systems for applying electrical signals to a packaged device or integrated circuit, or a device or integrated circuit chip on wafer, and measuring the response of the device or integrated circuit to the applied electrical signals. Specifically, one embodiment of the invention provides a calibration board for electrical connection to a test head of an electronic circuit tester for calibrating the tester to the plane of the test head. The calibration board in accordance with one embodiment of the invention is particularly adaptable to a high-frequency electronic circuit tester for effecting calibration of the tester for increasing precision of subsequent measurements of the response of the device or integrated circuit during actual testing, as well as for facilitating the setup and calibration of, and measurements with, the tester for testing high-frequency devices and integrated circuits, thereby improving reliability and enhancing overall throughput.
Programmable electronic circuit testers are typically used during the manufacture of electronic devices and integrated circuits to test the performance of the device or integrated circuit being manufactured. Tests are conducted to assure that the device or integrated circuit satisfies associated design performance specifications. In order to test the device or integrated circuit, the electronic circuit tester is programmed to inject an electrical signal or suite of electrical signals into the device or integrated circuit under test and to measure the response(s). The electronic circuit tester cannot only be used to test finished packaged devices and integrated circuits, but is also frequently used to perform tests at various stages of manufacture of the device or integrated circuit between initial wafer processing and final packaging.
A conventional programmable electronic circuit tester, generally indicated by the numeral 10, is shown in FIG. 1. The electronic circuit tester 10 comprises a test head 12 electrically connected by cables routed through a conduit 14 to a rack(s) 16 of electronic test and measurement instruments, such as ac and dc electrical signal generators for applying electrical signals to a device or integrated circuit interfaced to the test head, and signal analyzers, for example, an oscilloscope and a network analyzer, for measuring the response(s) to those applied electrical signals. As shown in FIG. 1, the test head 12 interfaces to a device or integrated circuit through a load board 18 connected to the cables in the conduit 14 and fixture board 20 in turn connected to the load board. Alternatively, prior to installation of the fixture board 20, a calibration board is preferably connected to the test head 12 for calibrating the electronic circuit tester 10. The configuration of the load board 18 depends on the type of device or integrated circuit being tested, such as an analog or digital electronic circuit, while the configuration of the fixture board 20 is typically specific to the family of device or integrated circuit being tested.
As shown in FIG. 1, the test head 12 is mounted on a dolly 22. Since the electronic circuit tester 10 can be employed to test both packaged devices and integrated circuits, as well as device or integrated circuit chips on wafer, the test head 12 is preferably mounted by pivotable connections 24 to the dolly 22. The pivotable connections 24 enable the test head 12 to be positioned in an approximately upward facing horizontal position so that the appropriate load board 18 and calibration or fixture board 20 can be mounted on the test head of the electronic circuit tester 10 by an operator. After calibration, the fixture board 20 is substituted for the calibration board, and the test head 12 can be pivoted to a vertical position so that the fixture board can interface with a material handler, for example, to test packaged devices or integrated circuits. Finally, the test head 12 can be pivoted to a downward facing horizontal position so that the fixture board 20 can interface with a wafer to test device or integrated circuit chips on the wafer.
Typically, calibration of the electronic circuit tester 10 has been performed with various calibration standards connected serially to connectors incorporated into the test head 12. This is a tedious procedure. Moreover, high-frequency coaxial connectors are relatively fragile, and the center conductor of such a connector can be damaged if caution is not exercised by the operator when connections are effected.
It would therefore be desirable to provide a calibration structure to efficiently calibrate the electronic circuit tester 10 during setup and calibration of the tester. Additionally, it is desirable to provide a relatively rugged calibration structure which is less susceptible to damage when connection is effected. Such a calibration structure would facilitate the use of the electronic circuit tester 10 to perform setup and calibration of the tester.